[rabbitmq-discuss] rabbitmq cpu usage can not be more than 700%

Jesper Louis Andersen jesper.louis.andersen at gmail.com
Tue Mar 12 17:36:20 GMT 2013

It is due to the way Erlang spins up more cores. The Erlang VM decides at
certain intervals how many cores it needs to satisfy the work it has. If it
never needs more than 7 cores to satisfy work, it will never spin up more.
Also note that it will keep a core "awake" even if there is no work to do
in the hope that work will arrive soon. So you cannot use a command like
top(1) to get any idea of what is happening.

The way is to get a shell on an erlang node and then use


in particular the scheduler_wall_time stats to get a grip on scheduler

My guess would be that you are bound by something else than CPU.

On Thu, Mar 7, 2013 at 9:14 AM, Xie Yunpeng <woqimingweipeng at gmail.com>wrote:

> rabbitmq version: 3.0.2
> cpu: 24 cores
> memory: 64G
> i deploy a rabbitmq service on the server above and do a stress testing ,
> use 150 threads for send and 300 threads for recv on 150 queues on the
> service, per queue with 1 send/ 2 recv.
> the cpu useage is always below 700%, no matter i increase queues and
> threads or not.
> how to use more than 7 cores in rabbitmq?
> i find smp is set to 24:24
> [rabbitmq]$ erl
> Erlang R15B03 (erts- [source] [64-bit] [smp:24:24]
> [async-threads:0] [hipe] [kernel-poll:false]
> Eshell V5.9.3.1  (abort with ^G)
> _______________________________________________
> rabbitmq-discuss mailing list
> rabbitmq-discuss at lists.rabbitmq.com
> https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss

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